Text2workspace fast simpdf

Dramatically speed up the time for creation on very complex workspaces by attaching the constraint terms only to the RooSimultaneousOpt at the very end, without introducing them in the pdf of each channel separately.

This feature is turned on by the --optimize-simpdf-constraints option in text2workspace

However tools who are not aware of the existence of RooSimultaneousOpt, e.g. plain RooFit or RooStats tools, will not see these constraints, and therefore won't be able to generate nuisance parameters or global observables correctly (but they will get them properly in the NLL since the createNLL method of RooSimultaneousOpt will call the implementation in combine, just as before, so fitting is ok)

A better solution to solve this by tackling the problem at the RooFit level will eventually be available (Lorenzo Moneta is looking into the issue), but that will require a new release so it's more for the future.
 
In addition, now running text2workspace with -v 1 will print out some more useful progress indicator